Projectile

ABSTRACT

A projectile of the type adapted to be propelled from a gun barrel by expanding gas. The projectile is formed with a chamber in its base and an outlet passage leading from the chamber through the base. The chamber is of nonuniform cross-sectional area with the cross-sectional area generally diminishing from a wall at the nose end of the chamber to the outlet passage. The wall of the nose end of the chamber may vary in shape from concave through flat to convex. The chamber may vary in shape from generally hemispheric to generally conical. In a modified form of the invention, at least two chambers are formed in the base and connected in series.

United States Patent [191 Scherr [54] PROJECTILE [75] Inventor: George H. Scherr, Park Forest, 111.

[73] Assignee: George H. Scherr, Park Forest, I11.

[22] Filed: Sept. 7, 1973 21 Appl. No.: 395,046

[ Oct. 21, 1975 463,491 4/1950 Italy 273/106 E Primary Examiner-Samuel Feinberg Assistant Examin'er*C. T. Jordan Attorney, Agent, or FirmKinzer, Plyer, Dorn & McEachran [5 7 ABSTRACT A projectile of the type adapted to be propelled from a gun barrel by expanding gas. The projectile is formed with a chamber in its base and an outlet passage leading from the chamber through the base. The chamber is of nonuniform cross-sectional area with the cross-sectional area generally diminishing from a wall at the nose end of the chamber to the outlet passage. The wall of the nose end of the chamber may vary in shape from concave through flat to convex. The chamber may vary in shape from generally hemispheric to generally conical. In a modified form of the invention, at least two chambers are formed in the base and connected in series.

13 Claims, 9 Drawing Figures [52] U.S. Cl. 102/92.1 [51] Int. Cl. F42B 11/00; F42B 13/00 [58] Field of Search 102/38, 41, 49.3, 49.7, 102/92.1, 92.2, 92.3, 92.4, 92.6, 92.7; 244/3.1, 3.2

[56] References Cited UNITED STATES PATENTS 279,539 6/1883 Chamberlain 102/49.3 2,408,252 9/1946 De Ganahl 102/38 X 2,821,924 2/1958 Hansen et al...... 244/328 2,982,550 5/1961 Francis 273/106 E 3,247,795 4/1966 Abela 102/38 3,450,054 6/1969 Robinson 102/38 3,486,451 12/1969 Moore et a1. 102/38 FOREIGN PATENTS OR APPLICATIONS 1,207,399 10/1959 France 273/106 E Sheet 1 of 2 3,913,487

US. Patent 0a. 21, 1975 US. Patent Oct. 21, 1975 Sheet 2 of2 3,913,487

1 PROJECTILE The principles that apply to the'science of ballistics have been appropriately described in numerous texts (Whelan, Townsend, Small Arm Design and Ballistics, Small Arms Technical Publishing Co., Georgetown, So. Carolina, 1945, Lowry, E. D., Interior Ballistics, Doubleday and Doubleday, Garden City, N.Y., 1968; Corner, John, Theory of the Interior Ballistics of Guns, John Wiley and Sons, Inc., N.Y., 1950;.and others).

In an analysis of the pressure resulting from theburning of the powder behind a projectile to be propelled, an average example cited by Lowry (op. cit.) could result in a pressure equal to 164,571 pounds per square inch (psi) utilizing the relationship.

PV nRT It appears clear, therefore, that it is necessary for the projectile to move some distance in the barrel of a gun while the propellant is still burning to avoid the dangerous high pressures that would result if all the propellant were to explode before the projectile was set in motion. The development of thrust against the projectile is best achieved if the expanding propelling gases have a flat surface against which to push, i.e., the flat end of the projectile. Merely increasing the cross sectional di ameter of the projectile, thus resulting in a larger and heavier bullet, other conditions remaining the same, would not result in an increased muzzle velocity be cause of the velocity squared V is inversely proportional to the weight of the bullet. Thus, attempts to decrease the weight of a projectile in order to increase its velocity have resulted in projectiles such as the Keith bullet in which the base has been partially hollowed out (Whelan, op. cit., pg. 317). A bullet designed by Ross (Whelan, op. cit., pg. 317) had a cored hollow base and a hollow point which design increased the accuracy of the projectile at long range. A hollowed-out projectile such as the Keith or Ross bullets would result in an increased velocity in accordance with the .formula:

[Energy of bullet (ft lbs)] [450,250] v1 weight of bullet T However, there would be little, if any, increase in the foot-lbs of energy of the bullet principally because the cross-sectional diameter of the bullet against which the expanding gases of the exploded propellant exert their thrust, has not increased (if anything, there might result a decrease of such thrust). A number of designs have been proposed to resolve this problem.

One design described by Corner (op. cit., pg. 334) has skirts attached to the projectile which skirts" provide increased cross-sectional surface against which the expanding gases exerted their thrust. The diameters of the skirts are wider than the cross-sectional diam-v eter of the projectile. As the projectile is forced along a gradually contracting bore, the skirts would be forced to contract thus reducing their diameters until the diameter of the bore was that of the skirts. A gradually contracting bore designed for such a contracting projectile would vary from a maximum of 28 mm to a minimum of 20 mm and would thus result in increased nozzle velocity.

Bullets have also been designed which contain a tail shoe against which the expanding gases develop a large thrust (Wallach, L.R., The Anatomy of Firearms, Simon and Schuster, N.Y., 1965 The tail shoe has a larger cross-sectional diameter than the bullet itself and then falls away when the projectile leaves the barrel having served its purpose; otherwise, it would result in an increased drag in flight of the projectile.

The invention described herein results in a projectile providing a larger area against which the expanding gases exert their thrust without effecting any change in the outer dimensions of the projectile or alteration in dimensions of the barrel.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of a projectile embodying the novel features of this invention with a portion shown in cross-section;

FIG. 2 is a side elevational view similar to that of FIG. 1 but showing a modified form of projectile;

FIG. 3 is a similar view of yet another modified form of projectile;

FIG. 4 is a similar view of still another modified form of projectile;

FIG. 5 is a similar view of the projectile having multiple interior chambers;

FIG. 6 is a view of a projectile similar to that shown in FIG. 1 but made in sections which are connected together and FIG. 7 is a side elevational view of another modified form of multiple chamber projectile;

FIG. 8 is a similar view of yet another modified form of projectile; and

FIG. 9 is a similar view of still another modified form of projectile.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One form of projectile ll embodying the novel features of this invention is shown in FIG. 1 of the drawing. The projectile includes a body 13 having a nose portion 15 and a base portion 17. A chamber 19 is formed inside the body and is connected to the base 17 by an outlet passage 21. An end wall 23 at the nose side of the chamber is flat. The side wall 25 of the chamber is hemispherical. The total surface area of the base 17, minus the area of the outlet passage 21, and the nose end wall 23 of the chamber 19 is greater than the total area of the base including the area of the outlet passage. In practice, the projectile of FIG. 1 would be propelled in the bore of a barrel as the propellant burns. Pressure of the expanding gases would be exerted over the surfaces 17 and 23 and the pressure per unit of surface area built up in chamber 19 would be the same as exerted against the base of the projectile.

In considering a gas that is uniformly distributed in a container, each of the molecules would have a velocity that can be characterized by a summation of the three Cartesian (Vector) components. Under such conditions of uniform distribution, the mass density of the gas (p) would be where m mass of molecules N number of molecules V container volume If the gas is non-uniformly distributed, then there occurs local mass densities in the container where the local mass density is p (X X X p (X,) in which X, is the position Vector with the three Cartesian components X X and X These and related principles have been discussed in much greater detail in such scholarly text as that of Vincenti and Kruger (Introduction to Physical Gas Dynamics, John Wiley & Sons, Inc., N. Y., 1965).

In the barrel chamber following the release of gases subsequent to an explosion designed to propel a projectile in such barrel, there is a non-uniform distribution of gases, their molecules, and relative mass densities of these gases due to the changing pressures against the projectile as it is forced along the barrel. The projectile moves out of the barrel due to such non-uniform local mass densities of gases compresses against the base of the projectile and it is such enhanced mass densities of gases compressed against the chamber nose and walls as submitted in the design of this invention which will enhance the forward propulsion of the projectile.

If we assume that the weight of a projectile such as depicted in FIG. 1 were to be exactly the same as a regular projectile of the same caliber and fired with a similar charge of propellant, two factors would tend to increase the velocity of the projectile 11 over a similar projectile not having such a chamber:

1. The increased surfacearea equivalent to the sum of areas 17 and 23 would result in a greater thrust behind the projectile.

2. The compressed gases in the chamber 19 would be decompressed following escape of the projecile from the bore and thus these gases would exert an additional thrust against the surface 23 as such compressed gases escape through the orifice 21.

The chamber formed in the projectile may vary considerably in shape and size without departing from the teachings of the invention. For example, in FIG. 2, the chamber 31 has a convex nose end wall 33 and hemispherical side wall 35. In FIG. 3 the chamber 41 has a concave nose end wall 43 and somewhat truncated hemispherical side wall 45.

The chamber 51 of the projectile of FIG. 4 has a flat nose end wall 53 and truncated conical side wall 55.

The projectile shown in FIG. has two chambers 61 and 63 connected in series by an intermediate passage 65. It should be understood that although the chambers shown are of the type of FIG. 1, the chambers may be of any of the other designs shown herein. Also, although both of the chambers 61 and 63 are of the same shape, it should be understood that the shape of these chambers may vary. For example, a chamber of the shape of chamber 19 could be used with a chamber of the shape of the chamber 31. Other combinations will suggest themselves to one skilled in the art. Also, although two chambers are shown connected in series, it should be understood that more than two chambers may be connected in series. The use of more than one chamber connected in series increases the total crosssectional area against which the expanding gases may act during movement of the projectile out of the barrel. Also, the additional chambers trap more compressed gas while the projectile is in the barrel and therefore more gas is expelled after the projectile leaves the barrel thereby increasing the thrust against the projectile.

FIG. 6 shows a projectile 71 made in parts. The projectile includes a solid nose portion 73 and a hollowed out base 75. The hollowed out portion of the base forms the chamber 77. An outlet passage 79 connects the chamber to the exterior of the projectile. The nose and base portions may be connected by a mortise and tenon type ring or other locking ring which is not shown.

FIG. 7 shows a projectile having two chambers 81 and 83 connected in series by an intermediate passage 85. Each chamber has a convex nose end wall 87 and a hemispherical side wall 89.

The projectile shown in FIG. 8 has two chambers 91 and 93 connected in series by an intermediate passage 95. Each chamber has a concave nose end wall 97 and a somewhat truncated hemispherical side wall 99.

The projectile shown in FIG. 9 has two chambers 101 and 103 connected in series by an intermediate passage 105. Each chamber has a flat nose end wall 107 and atruncated conical side wall 109.

It is understood that not all of the thrust exerted against the surfaces of the chamber by the expanding gases is positive since a certain amount of pressure will also be exerted against surfaces such as the hemispherical wall 25 of the chamber 19 of projectile 11 and similar surfaces of the side walls of other chambers. However, the net gain of forward thrust will be greater than that which would result against the surface of the flat end of the projectile if there were no chambers of the type and shape shown herein.

I claim:

1. A projectile adapted to be propelled from a gun barrel by expanding gas,

said projectile having a generally cylindrical body with a tapered nose at one end and a transversely extending fiat base at the opposite end,

a chamber formed in said body forward of the base with said chamber having a wall at the nose end thereof extending generally transversely of the projectile body, and

an outlet passage of generally constant transverse cross-section extending from said chamber through said base with the transverse cross-sectional area of said outlet passage being less than that of the transverse cross-sectional area of said chamber nose end wall,

the total transverse surface area of the base less the area of the outlet passage, and the transverse surface area of the nose end wall of the chamber being greater than the total transverse surface area of the base including the area of the outlet passage.

2. The projectile of claim 1 in which said chamber nose end wall is generally flat.

3. The projectile of claim 1 in which said chamber nose end wall is generally concave.

4. The projectile of claim 1 in which said chamber nose end wall is generally convex.

5. The projectile of claim 1 in which said chamber is generally hemispheric.

6. The projectile of claim 1 in which said chamber is generally conical.

7. The projectile of claim 1 in which a second chamber is located forwardly of said chamber and is connected thereto by a second outlet passage which leads from said second chamber through said nose end wall of said first chamber.

8. The projectile of claim 7 in which at least one of said chambers has a nose end wall which is generally 9. The projectile of claim 7 in which at least one of said chambers has a nose end wall which is generally concave.

10. The projectile of claim 7 in which at least one of said chambers is generally hemispheric.

12. The projectile of claim 7 in which at least one of said chambers is generally conical.

13. The projectile of claim 1 in which said body is said chambers has a nose end wall which is generally 5 made in portions and the portions of said body forming convex.

11. The projectile of claim 7 in which at least one of said chamber are detachable from said projectile. 

1. A projectile adapted to be propelled from a gun barrel by expanding gas, said projectile having a generally cylindrical body with a tapered nose at one end and a transversely extending flat base at the opposite end, a chamber formed in said body forward of the base with said chamber having a wall at the nose end thereof extending generally transversely of the projectile body, and an outlet passage of generally constant transverse cross-section extending from said chamber through said base with the transverse cross-sectional area of said outlet passage being less than that of the transverse cross-sectional area of said chamber nose end wall, the total transverse surface area of the base less the area of the outlet passage, and the transverse surface area of the nose end wall of the chamber being greater than the total transverse surface area of the base including the area of the outlet passage.
 2. The projectile of claim 1 in which said chamber nose end wall is generally flat.
 3. The projectile of claim 1 in which said chamber nose end wall is generally concave.
 4. The projectile of claim 1 in which said chamber nose end wall is generally convex.
 5. The projectile of claim 1 in which said chamber is generally hemispheric.
 6. The projectile of claim 1 in which said chamber is generally conical.
 7. The projectile of claim 1 in which a second chamber is located forwardly of said chamber and is connected thereto by a second outlet passage which leads from said second chamber through said nose end wall of said first chamber.
 8. The projectile of claim 7 in which at least one of said chambers has a nose end wall which is generally flat.
 9. The projectile of claim 7 in which at least one of said chambers has a nose end wall which is generally concave.
 10. The projectile of claim 7 in which at least one of said chambers has a nose end wall which is generally convex.
 11. The projectile of claim 7 in which at least one of said chambers is generally hemispheric.
 12. The projectile of claim 7 in which at least one of said chambers is generally conical.
 13. The projectile of claim 1 in which said body is made in portions and the portions of said body forming said chamber are detachable from said projectile. 